Paging method and apparatus for communication of m2m/mtc device operating in high power saving reception mode in a mobile communication system, and system thereof

ABSTRACT

method is provided for communicating with a User Equipment (UE) supporting a High Power Saving Reception Mode (HPSRM) mode by an evolved Node B (eNB) in a wireless communication system. The method includes receiving Discontinuous Reception (DRX) cycle information from a network entity performing mobility management for the UE by the eNB communicating with the UE over a wireless link; and broadcasting system information including the DRX cycle information. The DRX cycle information is set longer than DRX cycle information of a UE non-supporting the HPSRM mode. By doing so, an efficient paging method for an UE operating in the HPSRM mode may be provided.

TECHNICAL FIELD

The present invention relates generally to a paging method and apparatusin a mobile communication system, and more particularly, to a pagingmethod and apparatus for various devices operating in a High PowerSaving Reception Mode (hereinafter referred to as an ‘HPSRM’ mode).

BACKGROUND ART

Generally, mobile communication systems have been developed, aiming toprovide communication while securing mobility of users. Due to the rapiddevelopment of technologies, the mobile communication systems now canprovide not only voice communication services but also high-speed datacommunication services. Recently, standardization for Long TermEvolution (LTE), one of the next-generation mobile communicationsystems, is in progress in 3^(rd Generation Partnership Project (3GPP)).LTE is a technology aimed to be commercialized in around 2010 andimplementing high-speed packet-based communications at a data rate ashigh as 100 Mbps, which is higher than that currently available.Recently, many discussions have been made to provide various newservices to LTE communication systems. A typical one of the technologiesto be newly introduced may include Machine To Machine, Machine TypeCommunication (hereinafter referred to as ‘M2M/MTC’) communication.

M2M/MTC communication, also known as inter-device communication, refersto communication between an electronic device and an electronic device,or between an electronic device and a data server over a mobilecommunication network. In early 1990s when the concept of the M2M/MTCcommunication was first introduced, the M2M/MTC communication wasconsidered the concept of remote control, telematics, or the like andits derivatives market was very limited, but the M2M/MTC communicationhas grown into a big worldwide market for the last few years with thefast growth. The M2M/MTC technology may be used in the field ofautomotive telematics, logistic management, intelligent metering system,remote asset management system, Point-Of-Sale (POS) system, andsecurity-related industry. Compared with the existing mobile phones usedin the mobile communication system, M2M/MTC devices are recommended tooperate in an HPSRM mode with a low-power transmission power unit inorder to reduce the price of M2M/MTC communication modules. Otherwise,the price of the M2M/MTC devices may increase, hindering the widespreaduse of the M2M/MTC devices.

FIG. 1 illustrates a configuration example of a 3GPP UMTS/GPRS mobilecommunication system.

Referring to FIG. 1, a User Equipment (UE) 101 means a terminal deviceor a subscriber participating in the wireless communication, and the UE101 is wirelessly connected to a Node B (NB) 105. Node Bs 105, 110, 115,120, 125, and 130, wireless base station devices directly participatingin communication with UEs, manage their own cells. Radio NetworkControllers (RNCs) 140 and 145 control a plurality of Node Bs, andcontrol radio resources. The RNCs 140 and 145 are connected to a PacketSwitched or Packet Service (PS) network by a Serving GPRS Support Node(SGSN) 150. Connections between the RNCs 140 and 145 and the SGSN 150are called an Iu-PS interface, and transmit/receive PS controlsignaling. The SGSN 150 takes charge of various control functions, andmanages mobility of idle mode UEs. The SGSN 150 manages servicebilling-related data of each subscriber, and controls a function ofselectively transmitting and receiving the data it should exchange withthe UE 101, by means of the Serving RNC (SRNC) 140 managing the UE 101.A Serving Gateway (S-GW) 160, a device providing data bearers,generates/removes data bearers under control of the SGSN 150.

FIG. 2 illustrates a configuration example of a 3GPP LTE mobilecommunication system.

Referring to FIG. 2, a Radio Access Network (RAN) of the LTE mobilecommunication system includes evolved Node Bs (eNBs) 205, 210, 215, and220, a Mobility Management Entity (MME) 225, and a Serving Gateway(S-GW) 230. A UE 235 accesses an external network via the ENB 205 andthe S-GW 230. Each of the ENBs 205 to 220 corresponds to a combinedentity of the legacy NB and its RNC in the UMTS system described withreference to FIG. 1.

The ENB 205 is connected to the UE 235 through a wireless channel, andperforms a more complex function than the legacy NB. In LTE, since alluser traffics including real-time services based on the InternetProtocol (IP), such as Voice over IP (VoIP), are serviced through ashared channel, devices for performing scheduling by collecting statusinformation of UEs are required, and this operation is controlled by theENBs 205 to 220. The ENBs 205 to 220 take charge of controlling radioresources of their cells. One ENB generally controls a plurality ofcells.

To achieve the data rate as high as 100 Mbps, LTE uses OrthogonalFrequency Division Multiplexing (OFDM) as a wireless access technologyin a bandwidth of a maximum of 20 MHz. In addition, LTE employs AdaptiveModulation & Coding (AMC) that adaptively determines a modulation schemeand a channel coding rate depending on the channel status of UEs. TheS-GW 230, a device providing data bearers, generates/removes databearers under control of the MME 225. The MME 225, a device for takingcharge of various control functions and performing mobility managementfor idle mode UEs, is connected to a plurality of ENBs.

FIG. 3 illustrates an example of an existing paging procedure in a 3GPPLTE/UMTS/GPRS system, in which for convenience of description, theconventional paging procedures both in the LTE system and the UMTS/GPRSsystem are illustrated together.

In FIG. 3, reference numeral 301 represents a UE (or M2M/MTC device),reference numerals 302 and 304 represent an eNB and an MME,respectively, and reference numerals 303 and 305 represent an RNC/BSCand an SGSN, respectively, constituting the UMTS/GPRS system. The BaseStation Controller (BSC), an entity for controlling radio resources inthe GPRS system, performs a similar function to that of the RNC in theUMTS system. Reference numeral 306 represents an S-GW in theLTE/UMTS/GPRS system. Reference numeral 31 represents a paging receptiontime applied to the existing UE in the LTE system, and the pagingreception time refers to a specific radio frame, or a subframe in theradio frame. Reference numeral 32 represents a paging reception timeapplied to the existing UE in the UMTS/GPRS system, reference numeral 33represents a paging Discontinuous Reception (DRX) cycle in the LTEsystem, and reference numeral 34 represents a paging DRX cycle in theUMTS/GPRS system.

Referring to FIG. 3, upon receiving DownLink (DL) data for a specificUE, the S-GW 306 transmits a DL Data Notification message indicating thereception of the DL data for a UE, to the MME 304 and the SGSN 305,which are controlling the UE 301, in steps 331 a and 331 b. Uponsuccessfully receiving the DL Data Notification message, the MME 304 andthe SGSN 305 transmit to the S-GW 306 a DL Data Notification ACK messageindicating their successful reception of the DL Data Notificationmessage in steps 313 a and 313 b.

The MME 304 and the SGSN 305 transmit a Paging message to the eNBs 302and the RNCs/BSCs 303 existing in a paging area (e.g., Routing Area (RA)of the UMTS system and Tracking Area (TA) of the LTE system) where theUE 301 is located, in steps 321 a and 321 b, respectively. The Pagingmessage includes Identification (ID) information of the UE 301 subjectedto paging, and information based on which the eNB 302 and the RNC/BSC303 can calculate when they should transmit the Paging message on awireless/radio basis. For example, the latter information includes a UEpaging DRX cycle and a UE identity index value or UE id, which are usedas input values for calculating a radio frame and a subframe carryingthe Paging message. For more details, reference can be made to 3GPPstandard TS36.413.

Upon receiving the Paging messages in step 321 a and 321 b, the eNB 302and the RNC/BSC 303 calculate a time/timing for which they willwirelessly transmit a Paging message for a target UE, based oninformation included in the received Paging messages. This is because anidle mode UE, performing a power saving operation, generally wakes up atintervals of a paging DRX cycle and checks whether a Paging message isreceived at the wake-up timing, in step 331.

That is, the eNB 302 and the RNC/BSC 303 should transmit a Pagingmessage for the UE 301 in sync with the timing (e.g., a specificsubframe in a specific radio frame in the LTE system) for which the UE301 wakes up to receive a Paging message at intervals of the paging DRXcycle. Otherwise, the UE 301 may fail to receive the Paging message.Therefore, in terms of the input values, the method in which the UE 301calculates in step 331 a timing for which it wakes up to receive itsPaging message, should be the same as the method in which havingreceived the Paging message in steps 321 a and 321 b, the eNB 302 andthe RNC/BSC 303 calculate a timing for which they will transmit Pagingmessages for the UE 301. The UE 301 uses its UE id and a paging DRXcycle to calculate a timing for which it will receive a Paging message,while the eNB 302 and the RNC/BSC 303 use the UE id or UE id index, andthe paging DRX cycle to calculate a timing for which they will transmittheir Paging messages to the UE 301. For more details, reference can bemade to the 3GPP UMTS standards TS25.304 and TS25.413, and the 3GPP LTEstandards TS36.304 and TS36.413.

Referring to FIG. 3, the eNB 301 and the RNC/BSC 302 transmit Pagingmessages at intervals of the paging DRX cycle in sync with the pagingreception timing of the UE 301 (in steps 351 a & 353 a in the LTEsystem, or in steps 351 b & 353 b in the UMTS/GPRS system). If the UE301 has failed to receive the transmitted Paging message due to awireless error in steps 351 a and 351 b, the UE 301 does not access thesystem since it has no knowledge of the transmission of the Pagingmessage. In this case, since there is reply to the Paging message, theeNB 302 and the RNC/BSC 303 retransmit the Paging message in steps 353 aand 353 b, considering that the UE 301 has failed to receive the Pagingmessage. Upon successfully receiving the Paging message retransmitted insteps 353 a and 353 b, the UE 301 will make access to the system in step361, and upon detecting the access, the eNB 302 and the RNC/BSC 303 stopthe transmission of the Paging message, determining that the UE 301 hassuccessfully received the Paging message. In the absence of the accessby the UE 301, the eNB 301 and the RNC/BSC 303 may retransmit the Pagingmessage N1 times (the predetermined number of retransmissions) or for atime of a T1 timer.

However, the above-described procedure of FIG. 3 merely shows anoperation of receiving a Paging message by a UE such as the existingmobile phone in an idle mode. If an M2M/MTC device (or UE) supportingthe HPSRM mode (hereinafter referred to as an ‘HPSRM M2M/MTC device’)performs the procedure of FIG. 3 in an idle mode, the effects of theHPSRM mode may not be expected. Therefore, there is a need to newlydefine a paging procedure for M2M/MTC devices operating in the HPSRMmode using a low-power transmission power unit in the mobilecommunication network.

DISCLOSURE OF INVENTION Technical Problem

Exemplary embodiments of the present invention provide an efficientcommunication method and apparatus for User Equipments (UEs) operatingin a High Power Saving Reception Mode (HPSRM) mode in a mobilecommunication system.

Exemplary embodiments of the present invention provide an efficientpaging method and apparatus for communication of devices operating in anHPSRM mode in a mobile communication system, and a system thereof.

Exemplary embodiments of the present invention provide an efficientpaging method and apparatus for HPSRM M2M/MTC communication in a mobilecommunication system, and a system thereof.

Solution to Problem

In accordance with one aspect of the present invention, there isprovided a method for communicating with a User Equipment (UE)supporting a High Power Saving Reception Mode (HPSRM) mode by an evolvedNode B (eNB) in a wireless communication system. The method includesreceiving Discontinuous Reception (DRX) cycle information from a networkentity performing mobility management for the UE by the eNBcommunicating with the UE over a wireless link; and broadcasting systeminformation including the DRX cycle information. The DRX cycleinformation is set longer than DRX cycle information of a UEnon-supporting the HPSRM mode.

In accordance with another aspect of the present invention, there isprovided an evolved Node B (eNB) for communicating with a User Equipment(UE) supporting a High Power Saving Reception Mode (HPSRM) mode in awireless communication system. The eNB includes a receiver for receivinginformation from a network entity performing mobility management for theUE; a transmitter for transmitting information to the UE; and acontroller for generating system information including DiscontinuousReception (DRX) cycle information of the UE, received from the networkentity, and broadcasting the system information to the UE. The DRX cycleinformation is set longer than DRX cycle information of a UEnon-supporting the HPSRM mode.

In accordance with further another aspect of the present invention,there is provided a method for communicating with an evolved Node B(eNB) by a User Equipment (UE) supporting a High Power Saving ReceptionMode (HPSRM) mode in a wireless communication system. The methodincludes receiving system information including Discontinuous Reception(DRX) cycle information from the eNB; and calculating a DRX cycle forcommunication with the eNB based on the DRX cycle information. The DRXcycle information is set longer than DRX cycle information of a UEnon-supporting the HPSRM mode.

In accordance with yet another aspect of the present invention, there isprovided a

User Equipment (UE) supporting a High Power Saving Reception Mode(HPSRM) mode, and communicating with an evolved Node B (eNB) in awireless communication system. The UE includes a receiver for receivinginformation from the eNB; and a controller for calculating aDiscontinuous Reception (DRX) cycle for communication with the eNB basedon system information including DRX cycle information received from theeNB. The DRX cycle information is set longer than DRX cycle informationof a UE non-supporting the HPSRM mode.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a diagram illustrating a configuration example of a 3GPPUMTS/GPRS mobile communication system;

FIG. 2 is a diagram illustrating a configuration example of a 3GPP LTEmobile communication system;

FIG. 3 is a signal flow diagram illustrating an example of an existingpaging method in a 3GPP LTE/UMTS/GPRS system;

FIGS. 4 a and 4 b are signal flow diagrams illustrating a paging methodfor a device operating in an HPSRM mode in a mobile communication systemaccording to an embodiment of the present invention;

FIGS. 5 a to 5 c are flowcharts illustrating operations of an MME/SGSNand an eNB/RNC/BSC in a mobile communication system with the pagingmethod of FIGS. 4 a and 4 b;

FIG. 6 is a flowchart illustrating an operation of an HPSRM M2M/MTCdevice in a mobile communication system with a paging method accordingto an embodiment of the present invention;

FIG. 7 a is a block diagram illustrating a structure of an MME/SGSNaccording to an embodiment of the present invention;

FIG. 7 b is a block diagram illustrating a structure of an eNB/RNC/BSCaccording to an embodiment of the present invention; and

FIG. 8 is a block diagram illustrating a structure of an HPSRM M2M/MTCdevice according to an embodiment of the present invention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features and structures.

MODE FOR THE INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings. The presentinvention may, however, be embodied in many different forms and shouldnot be construed as being limited to the embodiments set forth herein.

The present invention provides an efficient method and apparatus fortransmitting a paging message to an HPSRM M2M/MTC device and allowingthe HPSRM M2M/MTC device to receive the Paging message.

While an HPSRM M2M/MTC device will be used as a device receiving apaging message in an exemplary embodiment of the present invention forconvenience of description, it should be noted that the presentinvention is not limited to the M2M/MTC device. In other words, thepresent invention may be applied not only to the HPSRM M2M/MTC devicesuch as various gauges, but also to various communication terminalsoperating in the HPSRM mode. Herein, the term ‘HPSRM’ refers to anoperation mode of minimizing the receive power consumed by a pertinentdevice during wireless/radio reception.

Although an MME and an eNB of the LTE system and an SGSN and an RNC/BSCof the UMTS/GPRS system will be used as network entities participatingin transmitting a paging message to an HPSRM M2M/MTC device in anembodiment of the present invention, the present invention may beapplied to other systems including network nodes having the same orsimilar functions. While exemplary embodiments of the present inventionwill be described with reference to the LTE system and the UMTS/GPRSsystem by way of example, the present invention is not limited theretoand may be applied in the same way to any cases in which a wirelessterminal operates in the HPSRM mode in various wireless communicationsystems transmitting/receiving paging messages. Herein, the eNB/RNC/BSCmay be referred to as, for example, an eNB or a base station, and theMME and the SGSN may be referred to as a network entity or a servermanaging mobility of UEs.

In an embodiment of the present invention, an MME/SGSN sets separatepaging DRX cycle information for reception of paging messages for HPSRMM2M/MTC devices, and transmits the set information to an eNB/RNC/BSC.The separate paging DRX cycle information may include, for example, anN2 value. The N2 value may include a multiple value of a paging DRXcycle allocated for the existing UE such as a mobile phone, or amultiple value of a modification cycle (e.g., modification cycle of theLTE system, for which reference can be made to 3GPP standard TS36.331)of intra-cell system information in a mobile communication system. Themodification cycle of system information may generally include amultiple value of a public paging DRX cycle. Also, the modificationcycle may include a modification of each of the above multiple values(for example, N2*10 ms). In an embodiment of the present invention, thepaging DRX cycle information is defined as an N2 value in theaccompanying drawings and the following description, for convenience ofdescription. Although the multiple value will be defined as a multiplevalue of the existing paging DRX cycle for a UE such as a mobile phone,it should be noted that the present invention is not limited thereto,and is subject to various modifications.

Upon receiving the paging DRX cycle information from the MME/SGSN, theeNB/RNC/BSC sets the received paging DRX cycle information as systeminformation, and broadcasts the set information to an M2M/MTC device(s)in its cell. Upon receiving the paging DRX cycle information as systeminformation, an HPSRM M2M/MTC device calculates a timing for which itwill receive a paging message from the system, using the existing pagingDRX cycle information for a UE such as a mobile phone, and idinformation of the M2M/MTC device.

For example, in the LTE system, an HPSRM M2M/MTC device checksreception/non-reception of a paging message for the M2M/MTC device at afirst paging message reception timing (e.g., a specific radio frame or aspecific subframe in the radio frame) calculated using the device id andthe existing paging DRX cycle for a UE such as a mobile phone. After thefirst paging message reception timing, the M2M/MTC device re-checks thereception/non-reception of a paging message after a lapse of (i)N2*‘existing paging DRX cycle for a UE such as a mobile phone’, (ii)N2*‘modification cycle of system information’, or (iii) N2 ms/s or N2*10ms. After the calculated first paging message reception timing, theM2M/MTC device checks the reception/non-reception of a paging message atintervals of the above extended paging DRX cycle rather than theexisting paging DRX cycle for a UE such as a mobile phone.

If DL data to be transmitted to a relevant M2M/MTC device(s) is receivedat an S-GW, an MME/SGSN transmits a paging message to its associatedeNB/RNC/BSC, and if a target device to receive the paging message is anHPSRM M2M/MTC device(s), the transmitted paging message includesinformation indicating that the target device to receive the pagingmessage is an HPSRM M2M/MTC device(s).

On the other hand, if the target device to receive the paging message isnot an HPSRM M2M/MTC device(s), the transmitted paging message includesinformation indicating that the target device to receive the pagingmessage is not an HPSRM M2M/MTC device(s). In the case where the targetdevice to receive the paging message is an HPSRM M2M/MTC device(s), ifthere is no response message/access for paging from the target M2M/MTCdevice described in FIG. 3 (in step 361 of FIG. 3), the eNB/RNC/BSC,having received the paging message, may retransmit the paging message N3times (where N3 represents the number of retransmissions and isdifferent from the number N1 of retransmissions) or for a time of a T3timer (which is different from a T1 timer) considering, for example, theN2 value as the proposed paging DRX cycle information broadcasted asintra-cell system information, instead of retransmitting the pagingmessage N1 times (where N1 represents a predetermined number ofretransmissions) or for a time of a T1 timer. This is because that sincea paging DRX cycle in which the HPSRM M2M/MTC device(s) checks thereception/non-reception of a paging message is longer by, for example, amultiple of N2 than the existing paging DRX cycle for a UE such as amobile phone, the number N1 of retransmissions or the time of a T1 timerbased on the existing paging DRX cycle may not reliably guarantee thereception of a paging message by the M2M/MTC device(s).

Therefore, if a target device to receive a paging message is an HPSRMM2M/MTC device(s), the number N1 of transmissions or the T1 timer valuedetermining the existing number of retransmissions for a paging messageshould be appropriately re-set as the number N3 of retransmissions or aT3 timer value, which is greater than the number N1 of retransmissionsor the T1 timer value, considering the N2 value which is paging DRXcycle information proposed by the present invention.

An embodiment of the present invention provides a method for setting anN2 value as paging DRX cycle information as described above, andallowing an MME/SGSN to transmit the N2 value to an eNB/RNC/BSC, and theeNB/RNC/BSC to broadcast the received N2 value as system information inthe cell. In the alternative, an operating method of determining the N2value as a prefixed value by the 3GPP standard, and an operating methodof notifying an upper layer of, as the N2 value, a value determined inthe upper layer of each of the M2M/MTC devices may also be available.

FIGS. 4 a and 4 b illustrate a paging method for a device operating inan HPSRM mode in a mobile communication system according to anembodiment of the present invention. The procedures of FIGS. 4 a and 4 brepresent an example of a paging method for an M2M/MTC device operatingin the HPSRM mode.

In FIGS. 4 a and 4 b, reference numeral 401 represents an HPSRM M2M/MTCdevice, reference numerals 402 and 404 represent an eNB and an MME ofthe LTE system, and reference numerals 403 and 405 represent an RNC/BSCand an SGSN of the UMTS/GPRS system. Reference numeral 406 represents anS-GW applied in common to the LTE system and the UMTS/GPRS system. Inthe drawing of FIGS. 4 a and 4 b, both the LTE system and the UMTS/GPRSsystem are illustrated. If only the LTE system is considered, the systemwill include the components 401, 402, 404, and 406, and if only theUMTS/GPRS system is considered, the system will include the components401, 403, 405, and 406.

Referring to FIGS. 4 a and 4 b, the MME 404 and the SGSN 405 set theabove-described separate paging DRX cycle information for reception of apaging message for the M2M/MTC device(s) 401 operating in the HPSRMmode, and transmit the set information to the eNB 402 and the RNC/BSC403 in steps 411 a and 411 b. The separate paging DRX cycle informationmay include, for example, the N2 value. Upon receiving the paging DRXcycle information from the MME 404 and the SGSN 405, the eNB 402 and theRNC/BSC 403 set the paging DRX cycle information as system information,and broadcast the set information to the M2M/MTC device 401 in the cellin steps 421 a and 421 b. Upon receiving the paging DRX cycleinformation as system information, the M2M/MTC device 401 operating inthe HPSRM mode sets a paging DRX cycle for reception of its pagingmessage in step 431.

In an embodiment of the present invention, the M2M/MTC device 401 mayuse the following schemes as the schemes of setting a paging DRX cycleby the M2M/MTC device 401.

Scheme 1: N2*‘existing paging DRX cycle’ (e.g., a paging DRX cycleapplied in common to cells and broadcasted as system information, for aUE such as a mobile phone)

Scheme 2: N2*‘modification cycle of system information’

Scheme 3: N2 ms/s or N2*10 ms

The modification cycle of the system information represents amodification cycle of the system information broadcasted by the eNB 402and the RNC/BSC 403 in the cell, and the system information may not bemodified within one system information modification cycle, and may begenerated/modified/deleted in a new system information modificationcycle. For the modification cycle of the system information, referencecan be made to the 3GPP standard TS36.331 for, for example, the LTEsystem, and to the 3GPP standard TS25.331 for the UMTS/GPRS system.

In steps 470 a and 470 b, the M2M/MTC device 401 calculates a timing(i.e., a location of a radio frame or a subframe in the radio framewhere a paging message is to be received, for example, in the LTEsystem, and a specific location of a channel in a radio frame where apaging message is to be received, for example, in the UMTS system) forwhich the M2M/MTC device 401 will receive a paging message, by using theexisting paging DRX cycle information for a UE such as a mobile phoneand id information of the M2M/MTC device 401 according to the existing3GPP standards (see the 3GPP UMTS standards TS25.304 and TS25.413, andthe 3GPP LTE standards TS36.304 and TS36.413), and checks thereception/non-reception of a paging message for the M2M/MTC device 401at a first paging message reception timing.

After the first paging message reception timing, the M2M/MTC device 401periodically checks the reception/non-reception of a paging message atintervals of the paging DRX cycle determined by any one of the Schemes1, 2 and 3 in steps 474 a to 478 a and 474 b to 478 b. That is, afterthe calculated first paging message reception timing, the M2M/MTC device401 checks the reception/non-reception of a paging message at intervalsof the paging DRX cycle extended by the above scheme (one of Schemes 1to 3), rather than the existing paging DRX cycle for a UE such as amobile phone.

Reference numeral 41 represents a paging message reception time appliedto a UE such as an existing mobile phone in the LTE system, andreference numeral 42 represents the time the HPSRM M2M/MTC device 401receives a paging message according to an embodiment of the presentinvention, in the paging message reception time applied to a UE such asan existing mobile phone in the LTE system.

Reference numeral 43 represents a paging message reception time appliedto a UE such as an existing mobile phone in the UMTS/GPRS system, andreference numeral 44 represents the time the HPSRM M2M/MTC device 401receives a paging message according to an embodiment of the presentinvention in the UMTS/GPRS system. In addition, each of hatched circlesillustrated in steps 474 a to 478 a and 474 b to 478 b corresponds toany one of the paging message reception times 41 to 44.

Reference numeral 45 represents a paging DRX cycle for the M2M/MTCdevice 401 in the LTE system, assuming that the paging DRX cycle is setaccording to, for example, Scheme 1 and an N2 value is 4. Referencenumeral 46 represents a paging DRX cycle for the M2M/MTC device 401 inthe UMTS/GPRS system, assuming that the paging DRX cycle is setaccording to, for example, Scheme 1 and an N2 value is 4.

In steps 441 a to 443 a and 441 b to 443 b, upon receiving anotification indicating the reception of DL data from the S-GW 406, theMME 404 and the SGSN 405 transmit a paging message to the eNB 402 andthe RNC/BSC 403 existing in the last registered paging area of thetarget device 401 to which the DL data is to be transmitted. If thetarget device 401 to receive the paging message is an M2M/MTC device(s)operating in the HPSRM mode, a paging message being delivered to the eNB402 and the RNC/BSC 403 includes identification information (orindicator) indicating that a target device to receive the paging messageis an M2M/MTC device(s) 401 operating in the HPSRM mode, in steps 451 aand 451 b.

On the other hand, if the target device to receive the paging message isnot an M2M/MTC device(s) 401 operating in the HPSRM mode, a pagingmessage delivered to the eNB 402 and the RNC/BSC 403 includes theindicator indicating that the target device to receive the pagingmessage is not an M2M/MTC device(s) 401 operating in the HPSRM mode, insteps 451 a and 451 b.

Upon receiving the paging message, the eNB 402 and the RNC/BSC 403calculate a timing for which the paging message is to be transmitted forthe target device, as described in FIG. 3. The transmission timing forthe paging message can be calculated using the conventional scheme,which may include the 3GPP UMTS standards TS25.304 and TS25.413, and the3GPP LTE standards TS36.304 and TS36.413, in step 461. Referencenumerals 471 a, 472 a, 473 a, 474 a, 475 a, 476 a, 477 a, and 478 arepresent examples of transmitting a paging message for the M2M/MTCdevice 401 at the calculated transmission timings in the LTE system.

Reference numerals 471 b, 472 b, 473 b, 474 b, 475 b, 476 b, 477 b, and478 b represent examples of transmitting a paging message for theM2M/MTC device 401 at the calculated transmission timings in theUMTS/GPRS system. The transmission timings 471 a, 472 a, 473 a, 475 a,476 a, and 477 a, and 471 b, 472 b, 473 b, 475 b, 476 b, and 477 b for apaging message are the timings at which the M2M/MTC device 401 does notactually check the reception of a paging message, since the M2M/MTCdevice 401 applies the paging DRX cycle that is extended from theexisting paging DRX cycle according to the N2 value which is the pagingDRX cycle information the M2M/MTC device 401 received. The M2M/MTCdevice 401 does not perform operations of receiving the transmittedpaging messages at the timings it does not check the reception of apaging message according to the N2 value.

Assume that reference numerals 474 a and 474 b represent timings atwhich the M2M/MTC device 401 actually checks the reception of a pagingmessage, but the M2M/MTC device 401 has failed to receive the pagingmessage due to a wireless error. Thereafter, upon receiving the pagingmessage at the timings 478 a and 478 b, the M2M/MTC device 401 makesaccess to the system in response to the paging message in step 481. Inthe above-described embodiment of the present invention, although apaging message is transmitted using the transmission timings in theprior art, the M2M/MTC device 401 checks the reception/non-reception ofa paging message with a reception timing longer than the existingtransmission timing by using the separate paging DRX cycle informationreceived from the system. Therefore, the M2M/MTC device 401 may maintainthe HPSRM mode, avoiding frequently checking the reception/non-receptionof a paging message.

In the case where the target device to receive the paging message is anHPSRM M2M/MTC device(s), in the absence of a response message/access forthe paging message from the target M2M/MTC device in step 481 asdescribed in the conventional technology of FIG. 3, the eNB 402 and theRNC/BSC 403 may retransmit the paging message N3 times (where N3represents a predetermined number of retransmissions and is greater thanthe number N1 of retransmissions) or for a time of a T3 timer (which isgreater than the T1 timer) considering the N2 value known as intra-cellsystem information, instead of retransmitting the paging message N1times or for a time of the T1 timer.

The reason for increasing the number of retransmissions is that sincethe paging DRX cycle in which the HPSRM M2M/MTC device(s) checks thereception/non-reception of a paging message is longer by a multiple ofN2 than the existing paging DRX cycle for a UE such as a mobile phone,the number N1 of retransmissions or the T1 timer value based on theexisting paging DRX cycle may not reliably guarantee the reception of apaging message by the M2M/MTC device(s).

Assuming that the existing paging DRX cycle is 640 ms, the number N1 ofretransmissions is 4, and the N2 value according to the presentinvention is 8, the M2M/MTC device(s) checks the reception/non-receptionof a paging message every 5120 ms (640 ms*8) in an embodiment of thepresent invention, and since the eNB/RNC/BSC transmits a paging messagefour times or for 2560 ms (640 ms*4), the M2M/MTC device(s) may notreceive the paging messages, which are not transmitted for the time of2560 ms. In another alternative, assuming that the existing paging DRXcycle is 640 ms, the N1 value is 8, and the N2 value is 8, a device(s)such as the existing mobile phone is granted eight opportunities tocheck the reception/non-reception of a paging message, so the device mayreceive a paging message reliably despite a wireless error, whereas theM2M/MTC device(s) is granted only one opportunity to check thereception/non-reception of a paging message due to an increase in thepaging DRX cycle by the N2 value, so the M2M/MTC device may hardlyreceive a paging message reliably upon a wireless error.

Therefore, if the target device to receive a paging message is an HPSRMM2M/MTC device(s), the number N1 of retransmissions or the T1 timervalue determining the existing number of retransmissions for a pagingmessage should be appropriately re-set as the number N3 ofretransmissions or a T3 timer value, which is greater than the number N1of retransmissions or the T1 timer value, considering the N2 value whichis paging DRX cycle information proposed by the present invention.

The embodiment of FIGS. 4 a and 4 b provides a method for setting an N2value representing a paging DRX cycle based on any one of Schemes 1 to3, and allowing an MME 404 and the SGSN 405 to transmit the paging DRXcycle information to the eNB 402 and the RNC/BSC 403, and the eNB 402and the RNC/BSC 403 to broadcast the paging DRX cycle information assystem information in the cell. In the alternative, an operating methodof determining the N2 value as a specific prefixed value by the 3GPPstandard, and an operating method of notifying an upper layer of, as theN2 value, a value determined in the upper layer of each of the M2M/MTCdevices may also be available. If the latter method is used,broadcasting the N2 value in the cell is optional.

FIGS. 5 a to 5 c illustrate operations of an MME/SGSN and an eNB/RNC/BSCin a mobile communication system with the paging method of FIGS. 4 a and4 b according to an embodiment of the present invention.

Specifically, FIG. 5 a illustrates an operation of the MME/SGSNperforming the paging method according to an embodiment of the presentinvention, and FIGS. 5 b and 5 c illustrate operations of theeNB/RNC/BSC.

Referring to FIG. 5 a, if there is a need for a separate operation ofreceiving a paging message for HPSRM M2M/MTC devices in step 501, theMME/SGSN sets separate paging DRX cycle information (e.g., N2 in FIGS. 4a and 4 b) for receiving a paging message for the M2M/MTC devices instep 511. In step 521, the MME/SGSN transmits the set paging DRX cycleinformation to associated eNB/RNC/BSC in step 521. In step 531, uponreceiving a notification indicating reception of DL data from an S-GW,the MME/SGSN checks whether a target device to which the DL data is tobe transmitted, or a target device to receive a paging message caused bythe DL data is an HPSRM M2M/MTC device(s), based on subscriberinformation.

If the target device is an HPSRM M2M/MTC device, the MME/SGSN sets anindicator (or identification information) indicating a paging messagefor an HPSRM M2M/MTC device(s) in the paging message in step 543, andtransmits the paging message to the eNB/RNC/BSC in step 551. On theother hand, if the target device is not an HPSRM M2M/MTC device(s) instep 531, the MME/SGSN sets an indicator indicating a paging message fora device other than an HPSRM M2M/MTC device(s) in the paging message instep 541, and transmits the paging message with the indicator to theeNB/RNC/BSC in step 551.

An operation of the eNB/RNC/BSC performing the paging method by thepresent invention will now be described with reference to FIG. 5 b. Uponreceiving separate paging DRX cycle information (e.g., N2 in FIGS. 4 aand 4 b) for receiving a paging message for an HPSRM M2M/MTC device(s)from the eNB/RNC/BSC in step 561, the eNB/RNC/BSC sets the receivedpaging DRX cycle information as system information and broadcasts theset information to the HPSRM M2M/MTC device(s) in the cell in step 563.

An operation of the eNB/RNC/BSC after broadcasting the systeminformation will be described with reference to FIG. 5 c. Upon receivingthe paging message with the indicator set therein from the MME/SGSN instep 571, the eNB/RNC/BSC checks the indicator in the paging message instep 581. If the paging message is a paging message for an HPSRM M2M/MTCdevice as a result of the check, the eNB/RNC/BSC calculates a timing forwhich a paging message is to be transmitted for a target device in aconventional manner, and transmits the paging message in the calculatedtransmission timing. Thereafter, in step 593, in the absence of aresponse (response message or response access) to the paging messagefrom the target M2M/MTC device, the eNB/RNC/BSC may iterativelyretransmit the paging message N3 times (where N3 represents the numberof retransmissions) or for a time of a T3 timer as described in FIGS. 4a and 4 b.

If the paging message is not a paging message for an HPSRM M2M/MTCdevice in step 581 as a result of checking the indicator, theeNB/RNC/BSC calculates a timing for which a paging message is to betransmitted for the target device in a conventional manner, andtransmits the paging message in the calculated transmission timing instep 581. Thereafter, in step 591, in the absence of a response(response message or response access) to the paging message, theeNB/RNC/BSC may repeatedly retransmit the paging message N1 times or fora time of a T1 timer as described in FIG. 3.

FIG. 6 illustrates an operation of an HPSRM M2M/MTC device in a mobilecommunication system with a paging method according to an embodiment ofthe present invention.

Referring to FIG. 6, an HPSRM M2M/MTC device acquires system information(e.g., N2 in FIG. 4) for receiving a paging message for M2M/MTC devices,broadcasted by the eNB/RNC/BSC, in step 601. In step 611, the HPSRMM2M/MTC device calculates a reception timing (i.e., a location of aradio frame or a subframe in the radio frame where a paging message isto be received, for example, in the LTE system, and a specific locationof a channel in a radio frame where a paging message is to be received,for example, in the UMTS system) for which the M2M/MTC device willreceive a paging message, by using the existing paging DRX cycleinformation for a UE such as a mobile phone and id information of theM2M/MTC device according to the existing 3GPP standards (see the 3GPPUMTS standards TS25.304 and TS25.413, and the 3GPP LTE standardsTS36.304 and TS36.413).

In step 621, the M2M/MTC device checks the reception/non-reception of apaging message for the M2M/MTC device at a first paging messagereception timing. In step 631, after the first paging message receptiontiming, the M2M/MTC device periodically checks thereception/non-reception of a paging message at intervals of a paging DRXcycle calculated by any one of above-described Schemes 1 to 3, e.g., apaging DRX cycle of (i) N2*‘existing paging DRX cycle for a UE such as amobile phone’, (ii) N2*‘system information modification cycle’, or (iii)N2 ms/s or N2*10 ms. In other words, after the calculated first pagingmessage reception timing, the M2M/MTC device checks thereception/non-reception of a paging message at intervals of the pagingDRX cycle extended by the above scheme (one of Schemes 1 to 3), ratherthan the existing paging DRX cycle for a UE such as a mobile phone.

Structures of network entities (or nodes) performing the paging methodof the present invention will be described below.

FIG. 7 a illustrates a structure of an MME/SGSN according to anembodiment of the present invention.

Referring to FIG. 7 a, the MME/SGSN includes a transceiver 701, amessage generation and analysis unit 711, and a database 721. Themessage generation and analysis unit 711 sets paging DRX cycleinformation (e.g., N2 in FIGS. 4 a and 4 b) for an M2M/MTC device, andtransmits the set information to its associated eNB/RNC/BSC through thetransceiver 701. The message generation and analysis unit 711 receives aDownlink Data Notification message indicating reception of DL data froman S-GW through the transceiver 701, and analyzes information includedin the received notification message.

The information contained in the notification message may includeinformation on a port number through which a device id or DL data hasarrived. The MME/SGSN may detect device/UE or user information from thedatabase 721 based on the above information. The MME/SGSN determineswhether a target device to which a paging message caused by reception ofthe DL data is to be transmitted, is an M2M/MTC device, using thedatabase 721 in which the analyzed information and the device/UE or userinformation are stored. The MME/SGSN generates a paging messageincluding an indicator indicating whether the target device is anM2M/MTC device, and transmits the generated paging message to theeNB/RNC/BSC via the transceiver 701.

FIG. 7 b illustrates a structure of an eNB/RNC/BSC according to anembodiment of the present invention.

Referring to FIG. 7 b, the eNB/RNC/BSC includes a transceiver 731, amessage generation and analysis unit 741, an information manager 751,and a scheduler 761.

The message generation and analysis unit 741 receives paging DRX cycleinformation for M2M/MTC devices and a paging message with the indicatorset therein from an MME/SGSN through the transceiver 731, analyzes thepaging DRX cycle information, stores the analyzed information in theinformation manager 751, generates paging DRX cycle information (e.g.,N2 in FIGS. 4 a and 4 b) for M2M/MTC devices as system information, andbroadcasts the generated information in the cell through the transceiver731. Upon receiving a paging message for an M2M/MTC device(s) from theMME/SGSN, the message generation and analysis unit 741 calculatescandidate timings at which the M2M/MTC device(s) will receive a pagingmessage, using the scheduler 761, and transmits the paging messagethrough the transceiver 731 at the calculated candidate timings.

The term ‘candidate timing’ refers to a timing applied forretransmission of a paging message. In the absence of a responsemessage/response access from M2M/MTC device(s) in reply to thetransmitted paging message for the M2M/MTC device(s), the messagegeneration and analysis unit 741 may retransmit the paging message atthe calculated candidate timings N3 times (where N3 represents thenumber of retransmissions) or for a time of a T3 timer, which arescheduled by the scheduler 761.

FIG. 8 illustrates a structure of an HPSRM M2M/MTC device according toan embodiment of the present invention.

Referring to FIG. 8, the HPSRM M2M/MTC device includes a transceiver801, a message generation and analysis unit 811, an information manager821, and a scheduler 831.

It is assumed that the HPSRM M2M/MTC device operates in an idle mode,and receives a paging message in an HPSRM mode according to the pagingreception timing of the present invention.

Upon acquiring paging DRX cycle information for an M2M/MTC device(s),which is broadcasted in the cell, from an eNB/RNC/BSC through thetransceiver 801, the message generation and analysis unit 811 analyzesthe paging DRX cycle information, and stores the acquired information inthe information manager 821 depending on the analysis. The informationmanager 821 stores the existing paging DRX cycle information, theM2M/MTC device id information, and the acquired separate paging DRXcycle information for M2M/MTC device(s), all of which are associatedwith reception of a paging message. The scheduler 831 determines a firsttiming for reception of a paging message and a paging DRX cycle to beapplied for succeeding paging reception, using the existing paging DRXcycle information for a UE such as an existing mobile phone, the M2M/MTCdevice id information, and the acquired separate paging DRX cycleinformation for an M2M/MTC device(s), and the message generation andanalysis unit 811 checks the reception/non-reception of a paging messageat the determined timing by means of the transceiver 801. Upon receivinga paging message, the message generation and analysis unit 811 generatesan uplink message, and makes access to the system through thetransceiver 801.

The above-described embodiment of the present invention is subject tovarious modifications.

For example, although it has been assumed in the above embodiment thatthe M2M/MTC device is an idle mode UE that receives a paging messageaccording to a paging DRX cycle, the same may be applied to aW-CDMA-based connected mode UE that operates at intervals of a DRX cycledetermined by, for example, network scheduling. In this case, if theconnected mode UE performs an HPSRM operation of an M2M/MTC device, awake-up cycle of the UE may be set longer than that of an ordinary UEnon-supporting the HPSRM mode by applying the above-describedembodiment.

The HPSRM operation of an M2M/MTC device may be performed in adevice-specific method that performs the HPSRM mode according to thetype of the device, or a service/data flow-specific method that performsthe HPSRM mode according to the type of the service/data.

In the above-described embodiment, in order for the network to determinewhether a specific UE is a UE operating in the HPSRM mode, the networkmay register information on UEs operating in the HPSRM mode in the meansfor storing subscriber information, such as, for example, a HomeLocation Register (HLR), or the UE may directly transmit to the networka registration message indicating that the UE itself is an M2M/MTCdevice.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

1. A method for communicating with a User Equipment (UE) supporting a High Power Saving Reception Mode (HPSRM) mode by an evolved Node B (eNB) in a wireless communication system, the method comprising: receiving Discontinuous Reception (DRX) cycle information from a network entity performing mobility management for the UE by the eNB communicating with the UE over a wireless link; and broadcasting system information including the DRX cycle information, wherein the DRX cycle information is set longer than DRX cycle information of a UE non-supporting the HPSRM mode.
 2. The method of claim 1, further comprising receiving a message to be transmitted to the UE from the network entity according to the DRX cycle information, wherein the message includes an indicator indicating that the UE is a UE supporting the HPSRM mode.
 3. The method of claim 2, further comprising determining a transmission timing for a message to be transmitted to the UE based on identification information of the UE.
 4. An evolved Node B (eNB) for communicating with a User Equipment (UE) supporting a High Power Saving Reception Mode (HPSRM) mode in a wireless communication system, the eNB comprising: a receiver configured to receive information from a network entity performing mobility management for the UE; a transmitter configured to transmit information to the UE; and a controller configured to generate system information including Discontinuous Reception (DRX) cycle information of the UE, received from the network entity, and broadcast the system information to the UE; wherein the DRX cycle information is set longer than DRX cycle information of a UE non-supporting the HPSRM mode.
 5. The eNB of claim 4, wherein the DRX cycle information includes information associated with a transmission cycle of a message transmitted to the UE.
 6. The eNB of claim 4, wherein the controller is configured to receive a message to be transmitted to the UE according to the DRX cycle information, from the network entity, and determine whether the UE is an UE supporting the HPSRM mode, and wherein the message includes an indicator indicating that the UE is a UE supporting the HPSRM mode.
 7. The eNB of claim 6, wherein the controller is configured to determine a transmission timing for a message to be transmitted to the UE based on identification information of the UE.
 8. A method for communicating with an evolved Node B (eNB) by a User Equipment (UE) supporting a High Power Saving Reception Mode (HPSRM) mode in a wireless communication system, the method comprising: receiving system information including Discontinuous Reception (DRX) cycle information from the eNB; and calculating a DRX cycle for communication with the eNB based on the DRX cycle information; wherein the DRX cycle information is set longer than DRX cycle information of a UE non-supporting the HPSRM mode.
 9. The method of claim 8, wherein the DRX cycle information includes information associated with a reception cycle of a message transmitted from the eNB.
 10. The method of claim 9, further comprising: calculating a first reception timing for which the message is received, based on the system information; and calculating an N-th reception timing (where N≧2) for which the message is received, based on the DRX cycle information.
 11. A User Equipment (UE) supporting a High Power Saving Reception Mode (HPSRM) mode, and communicating with an evolved Node B (eNB) in a wireless communication system, the UE comprising: a receiver configured to receive information from the eNB; and a controller configured to calculate a Discontinuous Reception (DRX) cycle for communication with the eNB based on system information including DRX cycle information received from the eNB; wherein the DRX cycle information is set longer than DRX cycle information of a UE non-supporting the HPSRM mode.
 12. The UE of claim 11, wherein the DRX cycle information includes information associated with a reception cycle of a message transmitted from the eNB.
 13. The UE of claim 12, wherein the controller is configured to calculate a first reception timing for which the message is received, based on the system information, and calculate an N-th reception timing (N≧2) for which the message is received, based on the DRX cycle information.
 14. The UE of claim 11, wherein the UE is an idle mode UE, and the DRX cycle information is associated with a transmission cycle of a paging message to be transmitted to the UE.
 15. The UE of claim 11, wherein the UE is a connected mode UE, and the DRX cycle information is associated with a cycle in which the UE wakes up according to scheduling.
 16. The method of claim 1, wherein the DRX cycle information includes information associated with a transmission cycle of a message transmitted to the UE.
 17. The method of claim 1, wherein the UE is an idle mode UE, and the DRX cycle information is associated with a transmission cycle of a paging message to be transmitted to the UE.
 18. The method of claim 1, wherein the UE is a connected mode UE, and the DRX cycle information is associated with a cycle in which the UE wakes up according to scheduling.
 19. The eNB of claim 4, wherein the UE is an idle mode UE, and the DRX cycle information is associated with a transmission cycle of a paging message to be transmitted to the UE.
 20. The eNB of claim 4, wherein the UE is a connected mode UE, and the DRX cycle information is associated with a cycle in which the UE wakes up according to scheduling.
 21. The method of claim 8, wherein the UE is an idle mode UE, and the DRX cycle information is associated with a transmission cycle of a paging message to be transmitted to the UE.
 22. The method of claim 8, wherein the UE is a connected mode UE, and the DRX cycle information is associated with a cycle in which the UE wakes up according to scheduling. 